After reading the previous discussion about a misaligned cylinder causing the grippers to smash the form, I thought about the SP20 I’m currently going over (and on which we have not yet printed) and noted that when I received it, the gripper bar was not at 12 oclock when the cylinder was home at the feedboard. I had assumed this was an error, so I rotated the cylinder by one tooth (counterclockwise) to get to 90 degrees, which is (seemingly) the proper position of the gripper bar on my SP15 when the cylinder is parked (never smashed anything on it). There were myriad other odd problems on this press when I received it, so I just assumed this reflected the previous owners idiosyncratic maintenance regime.
But a quick check with a piece of type and a peak under the cylinder, on trip, revealed that the grippers would smash type if used in this (now “fixed”, 12 oclock) position. So last night I reset the cylinder, took another peak– looks proper after all. Two questions: what is the spec on the proper angle of the gripper bar mounting surface on an SP20 when the cylinder is home? And why would this offset (one tooth off from 90) be designed into the cylinder– why not 90, which seems to me to allow for easier feeding to the grippers?
Hope that was clear, and thanks in advance for clarifying.
One more thing: Maybe this is old news, but to adjust the cylinder gear, I simply removed the mid sections of gear rack (which I had just been cleaning) on both sides of the bed and eased the cylinder foward on trip until the last tooth just cleared, rotated carefully, and then remeshed the teeth/rack and reversed. I did this adjustment once on my SP15 and removed the entire cylinder from the bed to do it. Now I know. Don’t know if this is inadvisable, or even applicable, to other models and their specific rack arrangements.
University of Hawaii
Department of Art